1. Field of the Invention
The present invention relates to a semiconductor wafer having a plurality of devices formed on a face side thereof and an adhesive film applied to the reverse side thereof, and a method of processing a semiconductor wafer, including the steps of grinding the reverse side of the semiconductor wafer to thin the semiconductor wafer and thereafter applying an adhesive film to the reverse side of the semiconductor wafer.
2. Description of the Related Art
According to the recent semiconductor device technology, stacked packages having a plurality of stacked semiconductor chips, such as MCPs (multi-chip packages) and SiPs (system-in packages) have effectively been utilized for higher packaging density and smaller size. The semiconductor chips of the stacked packages include die-bonding adhesive films called DAF (Die Attach Film) applied to the reverse sides thereof for holding the semiconductor chips stacked. Each of the adhesive films is made of a sticky resin material such as epoxy and polyimide, and is applied to the reverse side of the semiconductor wafer after the reverse side of the wafer is ground to thin the wafer.
It has been the general practice to grind the reverse side of a semiconductor wafer by holding the face side of the semiconductor wafer closely against a chuck table so that the reverse side thereof to be ground is exposed, and pressing a grinding wheel which is rotating at a high speed against the reverse side of the semiconductor wafer. A protective tape is applied to the face side of the semiconductor wafer to prevent the devices formed thereon from directly contacting the chuck table. The wafer is then diced into a plurality of individual chips. To dice the wafer, a dicing tape supported by a dicing frame is applied to the adhesive film on the reverse side, and the semiconductor wafer, the dicing frame, and the dicing tape are set on a wafer dicing device (see Japanese Patent Laid-Open No. 2005-276971). The wafer dicing device may be a dicing device for pressing a rotary blade into the semiconductor wafer to dice the semiconductor wafer or a laser device for applying a laser beam to the wafer to dice the semiconductor wafer. When the wafer dicing device is to dice the semiconductor wafer, the protective tape is peeled off the face side of the semiconductor wafer (see Japanese Patent Laid-Open No. Hei 5-63077).
Normally, the semiconductor wafer has its peripheral edge beveled to an arcuate surface extending from the face side to the reverse side for preventing the peripheral edge from being chipped when it undergoes shocks. When the reverse side of the semiconductor wafer is grounded to a thickness which is at least one-half its original thickness, the diameter of the semiconductor wafer becomes smaller than the original diameter. Therefore, the diameter of the protective tape applied to the face side of the semiconductor wafer becomes larger than the diameter of the semiconductor wafer, causing the protective tape to bring its peripheral edge close to the reverse side of the semiconductor wafer.
When the adhesive film is then applied to the reverse side of the semiconductor wafer, the portion of the peripheral edge of the adhesive film which projects outwardly from the peripheral edge of the semiconductor wafer tends to contact the peripheral edge of the protective tape. If the peripheral edge of the adhesive film contacts the peripheral edge of the protective tape, then the protective tape sticks to the adhesive film and cannot easily be peeled off therefrom. In the subsequent wafer dicing step, consequently, it is difficult to peel off the protective film from the semiconductor wafer. The trouble manifests itself particularly if the semiconductor wafer is very thin or the adhesive film is relatively thick and is heated when it is applied. Some dicing tapes have an adhesive tape integrally formed with one surface thereof. When such an adhesive tape is applied to the ground reverse side of a semiconductor wafer, the adhesive tape also tends to be brought into contact with the protective tape which then cannot easily be peeled off from the adhesive tape.